British Energy PLC said it received proposals from several parties wishing to make a full offer for the company, some of which were higher than the closing price of its shares Thursday.
The company's board said it reviewed the proposals and decided they require further development and discussions should continue, most likely for a number of weeks.
The nuclear-power generator said some of the offers were above Thursday's close 680 pence a share, valuing the company at about 10.85 billion GBP ($21.13 billion).
"There can be no certainty that any of the proposals will lead to an offer being made for the company nor as to the terms on which any offer would be made. A further announcement will be made in due course," the company said.
A bidding contest for British Energy is looking more likely, said Evolution Securities analyst Lakis Athanasiou.
British Energy shares on Thursday had fallen 115 pence, or 13%, since April 25, when hopes of a bidding war for the company began to fade. Friday, the stock rose 5.2%, or 35.50 pence, to 715.50 pence in a higher overall United Kingdom market.
The U.K. government wants to sell its 35.2% stake in British Energy, but the buyer of that holding would automatically have to make a bid for the whole company.
Electricite de France SA submitted a bid for British Energy on May 9, which was the tentative deadline given by the U.K. company's advisers, Rothschilds, according to a person familiar with the matter.
A number of European utilities, including the U.K.'s Centrica PLC, Germany's RWE AG and Spain's Iberdrola SA, are also interested in British Energy.